JP5480779B2 - Pre-coated aluminum plate - Google Patents

Description

  The present invention relates to an aluminum plate and an aluminum alloy plate used in a high-temperature environment such as automobile exhaust system members and heat-resistant structural members of home appliances, and relates to a precoated aluminum plate having a heat-resistant film provided on the surface of the aluminum plate by painting. .

  Surface treatment of aluminum plates (including aluminum alloys; the same applies hereinafter) used at high temperatures, such as automotive exhaust system members and heat-resistant structural members of home appliances, has been conventionally performed after forming the aluminum plate into a product shape. It has been carried out by a post coating method that forms a high inorganic film or a silicone resin film. However, the surface treatment is preferably performed by a pre-coating method in which a resin film is formed in advance on the surface of the aluminum plate before molding from the viewpoint of mass productivity, simplification of the manufacturing process, and cost reduction. The following are mentioned as a precoat material excellent in heat resistance manufactured by the precoat method.

  Patent Document 1 describes an oil-free, organic-coated metal plate excellent in heat resistance, in which an organic coating film containing a polyolefin wax and silica is formed on an ether / ester urethane resin and an epoxy resin. ing.

  Patent Document 2 proposes a coated metal plate in which a composite film formed by blending an alkali silicate glass aqueous solution with a particulate filler and a tetrafluoride fluororesin is formed.

  Patent Document 3 proposes a heat-resistant clear pre-coated metal plate in which a clear film is formed by dispersing a scaly inorganic powder such as alumina flake, mica powder, talc powder, or plate kaolin in an alkyl silicone resin.

JP-A-8-192102 JP 2000-319575 A Japanese Patent No. 4046322

  An exhaust system member or a heat-resistant structural member of an automobile may have a high temperature of 400 ° C. or higher during use. When Patent Documents 1 to 3 are used at such a high temperature, there are the following problems.

  The heat-resistant temperature of the urethane resin and epoxy resin described in Patent Document 1 is about 200 ° C. at the highest, and there is a problem that the resin starts to decompose in a high temperature environment higher than that.

  Moreover, although the composite film described in Patent Document 2 has good heat resistance, it tends to cause film cracking, peeling, and the like due to processing, and thus may not be able to cope with complicated processing. Moreover, if the product is used for a long time at a high temperature, the fluororesin may be decomposed to generate highly toxic fluorine gas.

  The film mainly composed of a silicone resin described in Patent Document 3 has no problem in heat resistance and safety, but the processability of the film is poor, and when complicated processing such as bending or drawing is performed, film cracking or film peeling occurs. Arise. For this reason, it is widely used in plate materials and members manufactured by the post-coating method, but uses such as flat plate or easy-to-process members are extremely limited as pre-coated plates.

  This invention is made | formed in view of the said condition, and makes it a subject to endure the high temperature of 400 degreeC or more, and to provide the precoat aluminum plate excellent in safety | security and workability.

  As a result of intensive studies to solve the above problems, the present inventors have found that the ratio of the aqueous resin, the silicate compound, the particulate inorganic filler, the particle diameter and the film thickness of the particulate inorganic filler are in a specific range. Thus, the inventors have found that the above problems can be solved, and have completed the present invention.

The precoated aluminum plate according to the present invention is a precoated aluminum plate in which a heat-resistant film is formed on the surface of the aluminum plate, and the heat-resistant film includes an aqueous resin, a silicate compound, and a particulate inorganic filler, The mass ratio of the resin / the silicate compound is 7 or more and 100 or less, the particle diameter of the particulate inorganic filler is 1 nm or more and 100 nm or less, and the mass ratio of the particulate inorganic filler / the silicate compound 1 or more and 100 or less, and the film thickness is 0.2 μm or more and 20 μm or less.

  Thus, the precoated aluminum plate according to the present invention is excellent in heat resistance, workability, and safety because the heat-resistant film contains an aqueous resin, a silicate compound, and a particulate inorganic filler. Moreover, since the mass ratio of the aqueous resin / silicate compound is 1 or more and 100 or less, the heat resistance and processability are excellent, and the particle size of the particulate inorganic filler is 1 nm or more and 100 nm or less, so that the appearance is excellent and the particulate form Since the mass ratio of the inorganic filler / silicate compound is 1 or more and 100 or less, the heat resistance is excellent. And since a film thickness shall be 0.2 micrometers or more and 20 micrometers or less, a favorable external appearance can be obtained.

The heat-resistant film in the precoated aluminum plate according to the present invention may further contain a color pigment.
By including a color pigment, it can be made excellent in design.

In the precoated aluminum plate according to the present invention, a topcoat film may be formed on the heat-resistant film.
By forming the top coat film on the heat resistant film, more excellent processability can be obtained.

The heat-resistant film in the precoated aluminum plate according to the present invention is preferably formed by baking at 160 ° C. or more and 260 ° C. or less.
By setting the baking temperature of the heat-resistant film to 160 ° C. or higher and 260 ° C. or lower, a film having excellent workability can be obtained.

  The precoated aluminum plate according to the present invention has a heat-resistant film having a specific range of mass ratio and film thickness of water-based resin, silicate compound, and particulate inorganic filler, and can withstand high temperatures of 400 ° C. or higher. And it is excellent in safety and processability.

It is a cross-sectional schematic diagram which shows 1st Embodiment of the precoat aluminum plate which concerns on this invention. It is a cross-sectional schematic diagram which shows 2nd Embodiment of the precoat aluminum plate which concerns on this invention. It is a cross-sectional schematic diagram which shows an example of 3rd Embodiment of the precoat aluminum plate which concerns on this invention. It is a cross-sectional schematic diagram which shows another example of 3rd Embodiment of the precoat aluminum plate which concerns on this invention.

  Hereinafter, an embodiment for carrying out the precoated aluminum plate according to the present invention will be described with reference to the drawings as appropriate.

[First Embodiment]
First, with reference to FIG. 1, 1st Embodiment of the precoat aluminum plate which concerns on this invention is described.
As shown in FIG. 1, the precoated aluminum plate 1 </ b> A according to the first embodiment is a precoated aluminum plate in which a heat-resistant film 3 is formed on the surface of the aluminum plate 2.

  The aluminum plate 2 only needs to be made of pure aluminum (Al) or an Al alloy. For example, 1000 series industrial pure Al, 3000 series Al-Mn alloy, 5000 series Al-- An Mg-based alloy or the like can be applied. Specifically, when drawing or ironing, A1050, A1100, A3003, and A3004 defined in JIS H4000 are recommended. A5052 and A5182 are recommended for applications where strength is desired. The tempering and the plate thickness are not particularly limited and can be selected according to the purpose.

The heat-resistant film 3 is provided for imparting heat resistance and workability to the precoated aluminum plate 1 of the present invention.
As shown in FIG. 1, the precoated aluminum plate 1 of the present invention is not limited to one in which only one surface of the aluminum plate 2 is coated with the heat-resistant film 3, and may be one in which both surfaces of the aluminum plate 2 are coated ( Not shown). The coating form can be freely selected according to the purpose.

  The heat-resistant film 3 includes an aqueous resin, a silicate compound, and a particulate inorganic filler 4. Such a heat-resistant film 3 can be formed by applying a paint mixed with these to the surface of the aluminum plate 2, baking the aluminum plate 2 to which the paint has been applied, and curing the paint.

  As a method of applying the coating material to the aluminum plate 2, any method such as brush coating, roll coater, curtain flow coater, roller curtain coater, electrostatic coating machine, blade coater, die coater, etc. may be used. The coating is preferably performed by a roll coater that is uniform in amount and simple in operation.

  In the coating, when the paint applied to the surface of the aluminum plate 2 is formed into a film by baking treatment, it is necessary to adjust the coating amount of the paint so that the film thickness is formed in the range of 0.2 μm to 20 μm. . By making the film thickness within this range, not only can the desired effects of the present invention be achieved, but also a continuous coat can be formed on the coiled aluminum plate 2 using a roll coater, resulting in excellent productivity. It is desirable in terms of cost. For example, when a roll coater is used, the application amount can be adjusted by appropriately setting the conveyance speed of the aluminum plate 2, the rotation direction and the rotation speed of the roll coater, and the like.

If the film thickness is less than 0.2 μm, the effect exhibited by the heat-resistant film 3 may not be sufficiently obtained. In particular, an unpainted part may occur and the appearance may be inferior. In addition, when a roll coater is used, it is necessary to increase the pressure between the pickup roll and the applicator roll, which is not preferable because the wear of the roll becomes severe.
On the other hand, even if the film thickness exceeds 20 μm, it is difficult to obtain further improvement. In addition, the lifting of the paint by the pick-up roll of the roll coater is insufficient, the variation in film thickness becomes remarkably large, and the appearance is inferior. The film thickness is preferably 3 μm or more and 18 μm or less, more preferably 3 μm or more and 10 μm or less, and further preferably 3 μm or more and 7 μm or less.

  In the case of the coating material applied as described above, for example, the baking treatment is preferably performed at a baking treatment temperature of 160 ° C. or higher and 260 ° C. or lower. When the baking treatment is performed at such a baking treatment temperature, a film can be suitably formed. When the baking temperature is less than 160 ° C., the film formation is insufficient and the adhesion with the aluminum plate 2 is also insufficient, so that the workability tends to be lowered. On the other hand, when the baking temperature exceeds 260 ° C., deterioration and decomposition of the coating starts, so that workability and adhesion tend to be lowered. The baking temperature is not so low from 160 ° C., for example, about 154 ° C., there is no problem in workability, and the temperature does not become so high from 260 ° C., for example, about 272 ° C. If there is no problem in workability. The baking temperature can be 166 ° C. or higher and can be 250 ° C. or lower. If it is the above-mentioned baking process temperature, a film can be formed by a short baking process of about 20 seconds to 50 seconds.

  Examples of the aqueous resin contained in the heat-resistant film 3 include acrylic resin, ethylene resin, epoxy resin, polyester resin, urethane resin, PVA (polyvinyl alcohol), PEO (polyethylene oxide), and CMC (carboxymethyl cellulose). One type selected from among them can be used, or two or more types can be mixed and used.

  Examples of the silicate compound contained in the heat-resistant film 3 include lithium silicate, sodium silicate, potassium silicate, or a mixture thereof.

  The particulate inorganic filler 4 contained in the heat-resistant coating 3 can be any inorganic particle colloid in which inorganic particles are dispersed in an aqueous solvent. Examples of the inorganic particle colloid include colloidal silica, alumina sol, zirconia sol, and titania sol. One kind selected from these can be used, or two or more kinds can be mixed and used.

The particle size of the particulate inorganic filler 4 is 1 nm or more and 100 nm or less. When the particle diameter of the particulate inorganic filler 4 is less than 1 nm or exceeds 100 nm, the heat-resistant film 3 becomes poor in appearance. In particular, when the particle size of the particulate inorganic filler 4 exceeds 100 nm, heat resistance cannot be obtained. The particle size of the particulate inorganic filler 4 is preferably 1 nm or more and 50 nm or less. The particle size of the particulate inorganic filler 4 is preferably 20 nm or less, more preferably 6 nm or less.
The particle size of the particulate inorganic filler 4 has a normal distribution, and the particle size of the particulate inorganic filler 4 in the present invention is a state of a colloid in which the particulate inorganic filler 4 is dispersed in an aqueous solvent or the like. The integrated volume 50% particle diameter measured with a laser diffraction particle size distribution analyzer or the like.

  The heat-resistant film 3 has a water resin / silicate compound mass ratio of 1 to 100. By setting the mass ratio of the aqueous resin / silicate compound within this range, the heat resistance and workability can be kept good. If the mass ratio of the aqueous resin / silicate compound is less than 1, sufficient processability cannot be obtained. On the other hand, when the mass ratio of the aqueous resin / silicate compound exceeds 100, heat resistance cannot be obtained. The mass ratio of the aqueous resin / silicate compound is preferably 3 or more and 93 or less, more preferably 7 or more and 33 or less, and still more preferably 14 or more and 33 or less.

  In the heat-resistant coating 3, the mass ratio of the particulate inorganic filler 4 / silicate compound is 1 or more and 100 or less. By making the mass ratio of the particulate inorganic filler 4 / silicate compound within this range, the film-forming property and heat resistance can be kept good. When the mass ratio of the particulate inorganic filler 4 / silicate compound is less than 1, a continuous film is formed even if a predetermined coating material containing an aqueous resin, a silicate compound, and the particulate inorganic filler 4 is applied. It is difficult and the appearance is poor. Moreover, when the mass ratio of the particulate inorganic filler 4 / silicate compound exceeds 100, it cannot withstand a high temperature of 400 ° C. or higher. That is, heat resistance cannot be obtained. The mass ratio of the particulate inorganic filler 4 / silicate compound is preferably 1 or more and 90 or less, more preferably 1 or more and 65 or less, and further preferably 1.5 or more and 6 or less.

[Second Embodiment]
Next, with reference to FIG. 2, 2nd Embodiment of the precoat aluminum plate which concerns on this invention is described.
As shown in FIG. 2, the precoated aluminum plate 1 </ b> B according to the second embodiment is a precoated aluminum plate in which a heat resistant film 3 further including a color pigment 5 is formed on the surface of the aluminum plate 2.

  The precoated aluminum plate 1B according to the second embodiment is different from the precoated aluminum plate 1A according to the first embodiment only in that it includes the color pigment 5. Therefore, configurations common to the first embodiment and the second embodiment are denoted by the same reference numerals and redundant description is omitted, and configurations that are different between these will be described below.

  The heat-resistant film 3 can be provided with a desired color by including the color pigment 5. The coloring pigment 5 is preferably an inorganic pigment having high heat resistance that does not decompose or discolor even at a high temperature of 400 ° C. or higher. For example, carbon black, titanium oxide, titanium black, copper / chromium black, cobalt black, manganese / iron black, copper / There are manganese / iron black, manganese / bismuth black and the like, and one kind selected from these may be used, or two or more kinds may be mixed and used.

[Third Embodiment]
Next, with reference to FIG. 3 and FIG. 4, 3rd Embodiment of the precoat aluminum plate which concerns on this invention is described.
As shown in FIGS. 3 and 4, the precoat aluminum plates 1 </ b> C and 1 </ b> D according to the third embodiment are obtained by forming a topcoat film 6 on the heat-resistant film 3.

  The pre-coated aluminum plate 1C shown as an example of the third embodiment and the pre-coated aluminum plate 1D shown as another example of the third embodiment are only different in that the top coat film 6 is formed on the heat-resistant film 3. It differs from the precoat aluminum plates 1A and 1B according to the first embodiment or the second embodiment. Therefore, configurations common to the first embodiment to the third embodiment are denoted by the same reference numerals and redundant description is omitted, and configurations that are different between these will be described below.

  The top coat film 6 formed on the heat resistant film 3 is preferably formed by applying an aqueous resin such as an acrylic resin, an ethylene resin, or an epoxy resin. By forming the topcoat film 6, workability can be improved. Further, the top coat film 6 can contain additives depending on the purpose. For example, carnauba wax, polyethylene wax, etc. can be added to improve lubricity, optical adjustment fine particles may be included to improve fingerprint resistance, and anti-booking to improve blocking resistance An agent can also be contained. These can be selected according to the purpose of use, and the kind thereof is not particularly limited. The top coat film 6 preferably has a film thickness of 0.2 μm or more and 5 μm or less in order to reliably exhibit the above-described effects.

  The precoated aluminum plate according to the first to third embodiments has been described above with reference to FIGS. 1 to 4. Since any plate aluminum plate is formed with a heat-resistant film having a specific range of mass ratio and film thickness of the water-based resin, silicate compound, and particulate inorganic filler, Excellent workability. In addition, since no fluororesin is used, even when heated to a high temperature of 400 ° C. or higher, highly toxic fluorine gas is not generated and the safety is excellent.

  The contents of the present invention are not limited to the contents described above. For example, in order to improve the adhesion between the aluminum plate 2 and the heat-resistant coating 3, and to improve the corrosion resistance, a base treatment layer (not shown) can be formed.

As the base treatment layer, a film containing one or more kinds selected from conventionally known Cr, Zr, and Ti can be applied. For example, a phosphate chromate film, a chromate chromate film, a zirconium phosphate film, a zirconium oxide film, a titanium phosphate film, a coating type chromate film, a coating type zirconium film, and the like can be used as appropriate. Moreover, you may make these films | membranes contain an organic component as needed. From the viewpoint of environmental consideration in recent years, it is preferable to use a phosphate chromate film that does not contain hexavalent chromium, a zirconium phosphate film, a zirconium oxide film, a titanium phosphate film, or a coating-type zirconium film. As a guideline, the thickness of the base treatment layer is preferably about 10 to 50 mg / m ^{2 in} terms of the amount of Cr, Zr, Ti deposited on the aluminum plate 2 (Cr, Zr, Ti converted value). If the adhesion amount is less than 10 mg / m ² , the entire surface of the aluminum plate 2 cannot be uniformly coated, and a sufficient effect cannot be obtained. On the other hand, when the adhesion amount exceeds 50 mg / m ² , the base treatment layer itself is likely to crack. The Cr, Zr, Ti converted value can be measured relatively easily and quantitatively by, for example, the fluorescent X-ray method. Therefore, quality control of the precoated aluminum plate can be performed without hindering productivity.

  Further, the surface of the aluminum plate 2 may be degreased before applying the paint for forming the heat-resistant film 3 to the aluminum plate 2. The degreasing of the surface of the aluminum plate 2 can be performed by, for example, spraying an alkaline aqueous solution on the surface of the aluminum plate 2 and washing with water.

  Next, the pre-coated aluminum plate according to the present invention will be specifically described with reference to examples satisfying the requirements of the present invention and comparative examples that are not.

First, an aluminum plate (JIS 1100-H24 material, plate thickness: 0.3 mm) was degreased with an alkaline aqueous solution as a base treatment, and then subjected to a phosphoric acid chromate treatment, and a phosphoric acid chromate film of 20 mg / m ^{2 in} terms of Cr. Was formed on both sides.

Subsequently, each coating material was prepared so that the mass ratio shown in Table 1 may be obtained for the types of aqueous resins, silicate compounds, and particulate inorganic fillers shown in Table 1. The prepared paint was applied to an aluminum plate using a roll coater. And the baking process of heating time 30 second is performed at the baking process temperature shown in Table 1, and the heat-resistant film | membrane which has the film thickness shown in Table 1 is formed. 1-29 were produced. The test material No. No. 16 was prepared by applying a paint and baking it without performing the above-described phosphoric acid chromate treatment after degreasing.
The numbers in parentheses “()” in Table 1 indicate parts by mass of each component in the film.

The heating method of the aluminum plate coated with the paint is a continuous baking method in which the aluminum plate coated with the paint moves from the inlet to the outlet of the oven, and the time for the aluminum plate to pass through the oven is the heating time. Adjusted to seconds. Moreover, the reached temperature of the aluminum plate confirmed with the heat label affixed on the aluminum plate was made into the baking temperature, and it adjusted so that this might become the temperature shown in Table 1.
The appearance, heat resistance, and workability of the prepared precoated aluminum plate were evaluated as follows.

<Appearance evaluation>
The appearance was evaluated by visually observing the surface of the prepared precoated aluminum plate, and the film was cracked, peeled off, blistered, unpainted, uncolored, or aggregated. Those having no abnormality were evaluated as good (◯).

<Evaluation of heat resistance>
Heat resistance was evaluated by heating the pre-coated aluminum plate in an air atmosphere at 400 ° C. for 24 hours. If the film disappeared compared to before heating, the film disappeared (x), and the film remained but discolored. Was evaluated as good (○), and a film that remained and did not change color was evaluated as excellent (◎).

<Evaluation of workability>
For the evaluation of workability, 5T and 3T 180 degree bending work specified in JIS K5400 was performed, and the film of the 5T 180 degree bending part peeled off with the cellophane tape was defective (x), and the film of the 5T 180 degree bending part was cellophane. The one that does not peel off with the tape is good (◯), and the one where the film of the 3T 180 ° bent portion does not peel with the cellophane tape is judged as excellent (◎).

  Table 1 shows the evaluation results of the appearance, heat resistance, and workability of the prepared precoated aluminum plate. The underline in Table 1 indicates that the requirements of the present invention are not satisfied.

Specimen No. Since Nos. 1 to 16 satisfied the requirements of the present invention, the appearance, heat resistance and workability were all good or excellent. Moreover, when evaluating heat resistance, no highly toxic gas such as fluorine gas was generated, and the safety was excellent.
On the other hand, the test material No. Since Nos. 17 to 29 did not satisfy any of the requirements of the present invention, any one of the appearance, heat resistance, and workability was defective.

Specifically, the test material No. No. 17 had poor workability because the mass ratio of the aqueous resin / silicate compound was less than 1.
Specimen No. No. 18 had poor heat resistance because the mass ratio of the aqueous resin / silicate compound exceeded 100.
Specimen No. In Nos. 19 and 20, since the particle size of the particulate inorganic filler did not satisfy the requirements of the present invention, the film had a poor appearance.
Specimen No. No. 21 had a poor appearance because the mass ratio of the particulate inorganic filler / silicate compound was less than 1.
Specimen No. No. 22 had poor heat resistance because the mass ratio of the particulate inorganic filler / silicate compound exceeded 100.
Specimen No. Nos. 23 and 24 had poor appearance because the film thickness did not satisfy the requirements of the present invention.

Specimen No. 25-29 are examples of the film | membrane of a composition different from this invention.
Specimen No. Since No. 25 used urethane resin, when it heated at 400 degreeC, the organic component decomposed | disassembled and heat resistance became defective.
Specimen No. For No. 26, an epoxy resin containing silica was used. When heated at 400 ° C., silica remained, but the epoxy resin decomposed, resulting in poor heat resistance.
Specimen No. Since No. 27 uses water glass containing glass powder particles as a particulate filler and a tetrafluorinated fluororesin, the heat resistance was good, but the workability was poor. Furthermore, since the film contains a fluororesin, a highly toxic fluorine gas was generated when heated at 400 ° C. Therefore, it was inferior to safety.
Specimen No. No. 28 had good heat resistance due to the use of a silicone resin, but had poor workability.
Specimen No. No. 29 is a film in which a top coat is provided on a silicone resin, but the workability was poor even when the top coat was provided.

  As mentioned above, although the precoat aluminum plate which concerns on this invention was demonstrated in detail by the form and Example for inventing, the meaning of this invention is not limited to these description, Description of a claim Should be interpreted widely.

1A, 1B, 1C, 1D Pre-coated aluminum plate 2 Aluminum plate 3 Heat resistant coating 4 Particulate inorganic filler 5 Colored pigment 6 Top coat coating

Claims (4)

A pre-coated aluminum plate having a heat-resistant film formed on the surface of the aluminum plate,
The heat-resistant film is
Including an aqueous resin, a silicate compound and a particulate inorganic filler;
The water resin / the silicate compound has a mass ratio of 7 to 100,
The particulate inorganic filler has a particle size of 1 nm to 100 nm,
The mass ratio of the particulate inorganic filler / the silicate compound is 1 or more and 100 or less,
A pre-coated aluminum plate having a thickness of 0.2 μm or more and 20 μm or less.   The precoated aluminum plate according to claim 1, wherein the heat-resistant film further contains a color pigment.   The precoat aluminum plate according to claim 1, wherein a topcoat film is formed on the heat-resistant film.   4. The precoated aluminum plate according to claim 1, wherein the heat-resistant film is formed by baking at a temperature of 160 ° C. to 260 ° C. 5.

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